There are existing systems which predict single words on the basis of a user “stroke” across a touch-sensitive keyboard/screen.
One such system, as disclosed in U.S. Pat. No. 7,098,896, titled “System and Method for Continuous Stroke Word-based text input”, comprises a store of words in a database. The method of predicting a word from the input stroke pattern comprises comparing the input stroke pattern with a set of the words in the database. The method comprises identifying a “final touch point” in the stroke pattern in order to identify the terminating character for a candidate word. Predictions for candidate words are then based on the first and last characters of the word, where these characters have been identified from the input stroke pattern. The actual path length of the inputted stroke pattern is compared to an expected path length which is stored with each word in the database of words.
An alternative approach to predicting a word from a continuous stroke has been disclosed in U.S. Pat. No. 7,251,367, titled “System and Method for Recognizing Word Patterns Based on a Virtual Keyboard Layout”. In this disclosure, stroke input patterns are compared, again within a single-word boundary, to a pre-determined library of stroke patterns. This technique has been demonstrated both with a completely pre-defined library and with a dynamically generated library.
All of the known systems, including those discussed above, are based around the principle of solving the problem of matching an input stroke, which is intended to represent a word, with a word in a database, based on the input stroke pattern and defined start and end points that correspond (approximately) to the start and end characters of individual words within the database.
The problem with the known systems and methods is that the input strokes are restricted to correspondence with the start and end characters of words in the database, requiring and restricting the user to enter strokes corresponding to full single words. Thus, the known systems and methods cannot predict words based on an input stroke which corresponds to the prefix of a word or an input stroke which corresponds to multiple words, for example where the user is trying to input a phrase with a single continuous stroke. It is an objective of the present invention to solve the above mentioned problems.